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Properties and Molecular Structure of Oxygen.Nucleophilicity and basicity difference.what is stability order of carbocations.Explain all chemical Test for alcohol and phenols.what are the list of tests for Aldehydes and Ketones.How shapes of molecules are related to the type of hybridization.How Ionic bond forms ? What are the properties.boiling point (liquid to vapours) etc, and are accompanied by absorption or evolution of heat. Such changes occur at definite temperature such as melting point (solid to liquid). The change of matter from one state (solid, liquid or gas) to another is called phase transition. The process will be spontaneous only when the total entropy increases. The entropy of the surroundings decreases.In general, there will be an overall increase of the total entropy (or disorder) whenever the disorder of the surroundings is greater than the decrease in disorder of the system.

In case of an exothermic process, the heat escapes into the surroundings and therefore, entropy of the surroundings increases on the other hand in case of endothermic process, the heat enters the system from the surroundings and therefore. (vii) Entropy, S is related to thermodynamic probability (W) by the relation,Įntropy changes in system & surroundings and total entropy change for Exothermic and Endothermic reactions Heat increases the thermal motion of the atoms or molecules and increases their disorder and hence their entropy. Unavailable energy = Entropy × Temperature (vi) Entropy is a measure of unavailable energy for useful work. The sum is called entropy change of universe. (v) The total entropy change of an isolated system is equal to the entropy change of system and entropy change of the surroundings. (iv) The change in entropy for a cyclic process is always zero. (iii) The change in entropy in going from one state to another is independent of the path. (ii) Entropy of a system is a state function. Its value depends upon the amount of the substance present in the system.

The important characteristics of entropy are summed up below In SI units, the entropy is expressed in terms of joule per degree Kelvin, i.e. Since entropy change is expressed by a heat term divided by temperature, it is expressed in terms of calorie per degree, i.e.,cal deg-1. The entropy change of a system may be defined as the integral of all the terms involving heat exchanged (q) divided by the absolute temperature (T) during each infinitesimally small change of the process carried out reversibly at constant temperature. It is more convenient to define the change of entropy during a change of state. It is difficult to define the actual entropy of a system. Entropy is represented by the symbol “S”. Entropy is a thermodynamic state quantity which is a measure of randomness or disorder of the molecules of the system.

Entropy change formula